change: add StartTransaction/EndTransaction method

examples/demo_test.go

@@ -18,6 +18,7 @@ var demoTestCase = &hrp.TestCase{
 			"varFoo2": "${max($a, $b)}", // 12.3; eval with built-in function
 		}),
 	TestSteps: []hrp.IStep{
+		hrp.NewStep("transaction 1 start").StartTransaction("tran1"), // start transaction
 		hrp.NewStep("get with params").
 			WithVariables(map[string]interface{}{ // step level variables
 				"n":       3,                // inherit config level variables if not set in step level, a/varFoo1
@@ -35,6 +36,7 @@ var demoTestCase = &hrp.TestCase{
 			AssertLengthEqual("body.args.foo1", 5, "check args foo1").            // validate response body with jmespath
 			AssertLengthEqual("$varFoo1", 5, "check args foo1").                  // assert with extracted variable from current step
 			AssertEqual("body.args.foo2", "34.5", "check args foo2"),             // notice: request params value will be converted to string
+		hrp.NewStep("transaction 1 end").EndTransaction("tran1"), // end transaction
 		hrp.NewStep("post json data").
 			POST("/post").
 			WithBody(map[string]interface{}{